Method of producing hypodermic needles



July 23, 1940.

METHon 0F PRODUCING YHYPODERMIC NEEDLES 2 Sheets-Sheet 1 Filed May 12, 1938 OR. Jsse Conrad Sm a'Z/i/ Afmmmfi July 23, 1940. J mm 2,208,606

METHOD OF PRODUCING HYPODERMIC NEEDLES Filed May 12, 1938 2 Sheets-Sheet 2 1 2 1a nu fi l smr Patented July 23,

UNITED STATES PATENT OFFICE U aammiv mz'rnon or raonucma HYPODERHIG Jesse-Conrad Smith, Merrick, N. Y. 7 Application my 1e, ms, Serial n 301,525 '3 Claims. (01; 29-148.-

This invention relates to'hypodermic needles and particularly to methods for their production. The ultimate object of my invention is the manufacture of improved hypodermic needles on a practical commercial basis and at reasonable cost.

My concept contemplates apparatus of an improved character and adapted for use in theproduction of such novel type hypodermic needle including swaging means adapted for use in one of the steps or operations in the productionof the hypodermic needles. I I

For a full understanding of the nature and obje'cts of the invention, reference should be had to '1 the following detailed-description taken in conaccording to my invention by such successive steps.

Fig. 4 is an end view of the needle of Fig. 3. Fig. 5 shows an enlarged transverse section on the indicated line 5-5, of Fig. 3. Fig. 6 illustrates a manner of and means for performing one of the die step operations. Fig. 7 is a. similar illustrative view of an operation and means for performing another step. I Fig. 8 is an enlarged vertically sectioned fragment illustrative of thearbor position.

Fig. 9 shows in illustrativefragment apart of a swaging apparatus according to my invention and in operation in carrying out one of the steps of the invention in the production of my novel needle.

Fig. 10 is a somewhat diagrammatic view of a form of swaging apparatus embodying the inven-- tion and adapted for carrying out the invention in the production of a needle such as exemplified.

Fig. 11 is a sectional viewon the line ll--l I, of

Fig. 10, and

Fig. 12 is an enlargedpartly sectioned view of"- ductile metals such as gold, have been largely discarded in favor of needles made of hard metal, in spite of various disadvantages in those hard metal needles which heretofore have been available. The steel needles in common use are 5 formed by securing the tubular point portion in a hub which is independent of the point portion, and have a marked tendency to break at the joint line where. the point portion meets the hub, due to the sharp fulcrum line at the joint, and often 10 V to crystallization resultingfrom soldering operations of blows delivered to join the parts. Another important desideratum is the provisionsof a needle hub portion which is sufficiently flexible or expansible so that it will fit over or held conformable to the nozzles of hypodermic syringes and even the contours of these nozzles which'are usually tapered and may vary slightly.'

In this connection it is to be understood that the term hypodermic needle as used herein is 20 intended to include tubular needles of a variety of sorts and is not limited to the common injection needle. l

, With the foregoing and other considerations in view, the present invention contemplates the pro- '25 vision of hypodermic needles which retain the desirable qualities of those in common use and which embody in addition one or more desirable features whereby various of the foregoing and other difliculties may be avoided. Among such 30 features are a reduced tendency'to break, a substantial freedom from roughness or adhering .particles or substances adhering in the bore, easy cleaning, and a facility in fitting the hub of the" needle on the nozzle of a syringe.- The invention 35 also contemplates the provision of an improved method whereby hypodermic needles and other thin-walled articles may be produced, and of improved apparatus directed tothls and similar ends.

1 In accordance with the invention there may be provided a hypodermic needle which is substantially free from breakagelines, which has a smooth longitudiniil contour both inside and outside, which is substantially free from adhering substances in its bore, and which has a hub portion which is sufliciently flexible to accommodate itself to the nozzle of a hypodermic syringe.

Such a needle may be formed in one piece from a single piece of sheet metal. one-piece construction is highly advantageous.

The metal used is desirably stainless steel, but in the broader aspects of theinvention may be any metal or alloy which or which by treatment such as hardening, and tempering maybe The provision of Q made to possess the desired hardness and other qualities, and which has enough ductility to permit it to be pressed and swaged in accordance with the invention.

In accordance with the invention a disc-like piece of sheet metal may be pressed into an elongated cup-like member. When the cup-like member has been suiliciently elongated and suitably shaped,. as by die-pressing, the end which corresponds to the center of the die may, in carrying out the invention, be elongated into needleform by a succession of swaging operations, each involving a series of intermittent pounding or squeezing actions which will be designated herein as blows, delivered at diiferent points on the work. In connection with the invention,

the position of the work is adjusted only in the intervals between the blows so that the work is subjected to no torsional stress such as would set Each swagup lines of weakness in the needle. ing portion is conducted on an arbor which prevents the occlusion of a bore. The arbors used are in general of decreasing size. The arbor is preferably, in accordance with the invention, adjusted so that its effective pressure-receiving portion extends substantially to, but not any considand to provide a needle which is substantially clean and semi-polished both inside and out.

Further surety against the presence of adhering substances may be obtained by conducting the annealing operations in an inert atmosphere and by conducting any hardening or tempering operations in an inert atmosphere. The pressing and swaging operations may be so performed that the outer surface of the needle is smoothly curved longitudinally'where the point portion Joins the hub portion, so that tendencies toward breakage at this point are substantially eliminated, and the bore of the needle may be smoothly curved longitudinally between the wide portion of the hub and the interior of the point portion so that a cleaning wire will encounter no obstructions when'inserted through the hub portion and so that there are no corners or edge portions to collect sediment or to interfere with the cleaning of the tube. Furthermore, byso conducting the swaging operation that there is no torsional stress on the needle during the swaging, and by the formation of the needle froma cup-like member pressed from a disc-like portion of metal, lines of weakness, whether in the nature of cleavage lines, seams, or other breakage lines, are avoided, and breakage due to such causes is substantially eliminated.

One product of the invention is shown in the form of a hypodermic injection needle in Figs. 3 and 4. As will be seen, the needle comprises a base or hub portion 0 and a cannula point portion it, which as integral portions are formed of a single piece of flat: sheet metal. The. metal should be such that it will have or take sufllcient hardness so that the point of the needle will remain sharp so long as, or. longer than, the points of the present steel needles in common use. The needle is formed without seams or breakage lines and has a thin wall throughout its extent. Its

exterior flares outwardly insmooth-longitudinal The curves throughout the part where the hub portion'and the point portion merge so that there are no sharp fulcrum lines which would be conducive to breakage. needle is likewise smoothly curved longitudinally so as to be without shoulders or pockets which would interfere with easy washing or would obstruct the movement of a cleaning wire. The point portion terminates in a sharp point ll. The inner surface of the hub has a slight taper to fit about the nozzle of a hypodermic syringe. The bore of thepoint portion of the needle may be .005" in diameter, and the wall of this portion may be .005" thick. The wall of the hub portion may have a thickness in the neighborhood of .020", if desired. Due to the uniform, thin contour of the upperportion of the hub, the hub has suflicient flexibility to fit snugly over a syringe nozzle having a periphery which does not conform with exactitude to the internal-contour of the hub. The needle is substantially free from breakage lines of any type, and in accordance with the invention, the point portion is semipolished both inside and out and is substantially free from surface irregularities and from adhering particles or substances which would toughen the surface or come loose in use. I

In Figs. 1 and 2 there are exemplified certain significant ones of a series of steps in a method which illustrates the invention and whereby a thin-walled tubular article maybe produced. As so exemplified the method is adapted for the production of a needle such as shown in Fig. 3. This method involves turning up the edges of a disc-like piece of sheet metal to form a cuplike member. For example, a disc of stainless steel (or other suitable metal) as indicated at A. may be pressed into the contour indicated at B. A disc about the diameter of a quarter of 8. doilar, and 0.17 of an inch in thickness may be utilized for the production'of a hypodermic injection needle of the usual size. If desired, a disclike piece may in a single operation be cut from a large sheet of metalfand shaped to assume the conformation shown at B. By successive operations this may be pressed into successively elongated shapes which may include those shapes The inner surface of the shown at C, D and E- The shaping of the mem ber may be conducted in any desired manner, for

instance in a punch press such as-shown in Fig. 6, wherein a suitably sized plunger l1 serves to press the member l8 through suitably proportioned and positioned dies Hand 20, which are desirably formed of tungsten carbide. The shaped piece may be removed by pressingthesame through segments, two of which are indicated at outwardly tapered conformation to provide a hub which will fit firmly over the tapered nozzle of a hypodermic syringe. The hub walls may be readily thinned down during certain of the pressv ing operations in cases where a thick initial sheet was used or where the early pressing operations tended to thicken the walls. A desirable wall thickness is from .015 to .020 of an inch, 'but, even when the thickness is Iconsiderably greater, the

V hub will have suflicient flexibility to conform easily to tapered syringe nozzles of slightly varying alsobeformedatflierimoi Eli contours. As likewise indicated at G, a bead may the member. The provision'of the head at this stage of the operation facilitates the holding of the needle during subsequent operations. The taper and bead-maybe provided by apparatus such as indicated in Fig. I, wherein a plunger 2! having a tapered end 26 thrusts the member between tapered'diesfl and 2|. The dies are so shaped that the upper end of'thecup-like member pro trudes above them, andjthe plunger carries an external portion 2! which bends this upper end over to form a bead 24, and to member, as indicated at G. v

The cup-shaped member may be annealed between any of the pressing p rations to overcome the work-hardening which results from the pressing. Such annealing is of particular importance in the treatment of a chrome metal such as above indicated, or other work hardening metal. In order to prevent the formation of scale which may aflect the smoothness of the needle and which will cut the dies, the invention contemplates the conductingof the annealing steps in an inert atmosphere.

In accordance with the invention, a point portion may be formed. on the cup-like member by a series of swaging operations in each of which the reduced end is squeezed inwardly against an arbor by a series of external blows. Intermediate the swaging operations the needle may be subjected to annealing operations. This is particularly important in the treatment of stainless steel. The swaging operations which act to squeeze the work against the arbor serve to provide a smooth, semi-polished surface both on the inside and the outside of the point portion, and to work loose and remove any scale formed in any previous annealing operation or any particles or substances which would otherwise cause a roughness in the surface or come loose in use. Any desired number of swaging operations may be utilized to successively elongate the point portion of the needle to provide constructions, certain of which are indicated at H, I, J and K, in Fig. 2. To perform any of these operations there may be utilized swaging apparatus of any desired character, whether of a. type wherein the work is adjusted with respect to stationary blow-delivery means, or

wherein the blow-delivery means, are adjusted with respect to the work, or if desired where both members are adjusted. It is highly important, however, that no relative adjustment of-the blowdelivery means and the work-holding means should occur while the work is gripped by the blow-delivery means, and particularly that no relative rotary movement take place, since the resultant twisting or other strain on the tube tends to weaken the tube and to form cleavage lines. A needle with a twisted cannula. is not only readily broken, but is likely to contain irregularities inits wall. t

In the carrying out of these annealing operations the member should be heated to its critical temperature-in the case of steel members to -a point just under the point where it begins. to lose its magnetism-and allowed to cool oil slowly. In' order to prevent the formation of oxides as before suggested, the invention in its more specific aspects contemplates conducting the annealing step in a vacuum or in an inert atmosphere. Such'an atmosphere may consist of 95% hydrogen and 5% nitrogen, and should preferably be pretreated. to eliminate-moisture. The avoidance of oxide formation is important, particularly in provide a cup-like member is straightened die 3| to press it against the work. There is prothe treatment of stainlesssteel, not only because of the undesirability of scale on or in the needle, but also because oxide tends to cut the dies and other working members. By way of example, there is illustrated in Figs.

9, -l2, a form of swa'ging apparatus adapted for the carrying out of the invention. The form of constructions illustrated comprises a stationary swaging die 30, and an opposed movable swaging die 3|. The work to be swaged, such as the point portion of a needle 32 is held ina suitable posi-;

tion between the dies and ii, To this end there is provided a work-holding member 33. which extends slidably through frame members 34' and. 35, and which carries a tapered butt 3 Fig 9) fitting within the hub of the needle, and pivotally supported lugs 3'! which extend under the, bead 24.

Within the needle between the dies there ex- 7 tends the end of the arbor 38, which may be soldered within a tube 39, extending to amicroa metrically adjustable head 4.. By shifting the head 40, the arbor may be drawn upwardly to permit a new needle. to be put in place andby adbe brought to just the right position between the dies. The work-holder a: is slidableon the tube 39 and is threaded through a threaded semi-circular opening 4| in a brace 42 so that the same may be longitudinally adjusted-by rotating moveafter unscrewing a in place the work holder is raised by swinging the brace." out-' wardily.

In order to deliver the blows, and to adjust the work holder, in the periods between the blows, there is provided mechanism comprising'a driving shaft 46, a fly wheel 41, acrank 48, and a link 49, which serves to operate a plunger 50. The plunger carries a. toggle member 5| connected with a sliding block 52 which, when the toggle out bears against the vided a toggle member 53, opposite the member 5|, and the toggle members are held within'recesses 54 and 55 in the plungers by means of springs 56. The downward movement of the needle itself. tends to spread the dies the required distance, which may be fivethousandths of an inch, between each blow. when the plunger moves upwardly or downwardly past center the member 52 is withdrawn and the die 3| relieved of pressure. At this period the work may be r0 ,tated and lowered without harm, and to this end the work holder 33 is provided with an external ratchet 51 against which a pawl 58 on one end of a swinging member 53 supported at 6!! is adapted to work. The other end of the member 59 carries a roller 6| which is drawn toward the plunger 50 by a spring 62. The plunger at this point is recessed, as indicated 'at 63, so that the member 59 is inefiectlve to turn the ratchet when the toggle 5| is in horizontal position. When, how ever, the plunger is at the lower or upper end of a stroke and the dies are apart, the roller rides forwardly on one of the shoulders 64 and 65 at the ends of the recess and swings the member 55 forwardly to rotate the ratchet 51 the extent of one notch on the ratchet. The work holder is rotated and the'work turned and lowered. The ratchet 'may be formed withsixty-one notches, the workholder provided at its threaded portion with twenjusting the head the lower end of the arbor may .2.

may be rotated therety threads to the inch, and the shaft 46 is driven at 1750 R. P. M.

It'will be apparent that the size of the arbor used in any particular operation will be dependent upon the size of the bore of the tube to be formed by the swaging operation, and that in general, arbors of decreasing size will be employed for successive swaging operations on the same needle. 7

In carrying out the swaging operation, it is also of importance that the arbor'project sulficiently far into the blow-delivery or pressure means, but-not too "far into it. Thus the efiective portion of the arbor should be far enough in so-that there will be no further reduction in the bore of the cannula by the blow-delivery or pres-' sure means, after the metal has left the eflective end of the arbor. Also, it should not be far enough in so that the arbor, in a small size, will be swaged and possibly broken by the blow-delivery or pressure means; or, ii the arbor be large enough or hard and strong enough to resist this swaging, so that it will not be bound inside the cannula so tightly as to prevent or make diiiicult its removal.

As will be apparent from Figs. 8 and 9, the swaging dies and ii are formed with curved portions a and with straight portions b which meet in a line 0 providing a circle oi. tangency. The arbor 38 should extend far enough'into the tubular member 32 so that a full diameter effective portion of the arbor reaches the circle or tangency and preferably extends beyond it slightly,

but not to suflicient extent that a marked binding action will ensue. In forming hypodermic needles of the usual size, there are desirably employed dies having a curved portion which at the part where they bear against the work conform generally to a curve having a radius of about one inch, and the arbor preferably is adjusted, as by the member 44, so that it extends about 9. 32nd of an inch beyond the circle of tan'gency, as to the line d in Fig. 8.. It is to be notedthat in these swaging operations wherein a cannula having a large outside diameter and a thinner wall than is desired for the final product'is reduced to have a smaller outside diameter and a thicker wall, the position of the arbor-becomes of less importance, inasmuch as the pressure of the work against the proper size arbor is less; but as will be apparent it is ordinarily desirable, even in these instances that the arbor be adjusted generally as indicated above.

When the formation of the needle is complete, the needle is desirably treated to increase its hardness. For example, a needle formed of Carpenters No. 2 stainless-steel oi the usual dimensions may be inserted in a furnace at a temperature of 1850" F. and held there iorhalf a minute. The atmosphere of the furnace shown should bean inert. gas, for example 95% hydrogen and 5% nitrogen which is substantially com:- pletely tree from moisture to prevent oxidation. On removal from the furnace the .needle is quenched in oil it toughness is desired, .or in wa-- ter. is especial hardness is desired, or in other suitable medium. It is then tempered in a furnace containing the same gas at a temperature oi! 400 F. and again quenched. It may then be polished, and given a sharp point such as indicated at H.

The point portion or cannula may be cut away to suitable length after the last swaging operation. It may then be ground at an angle of 30, and lapped to a sharp point. The burrs formed by grinding may be removed either before lapping or simultaneously with lapping.

Since certain changes may be made in the above articles and in the method and construction set forth without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What I therefore claim and desire to secure by Letters Patent is:

1. The method of forming a seamless, onepiece hypodermic needle comprising a hollow hub portion of relatively large diameter for engagement with the tapered and tips of Luer or like syringes, a thin walled tubular cannula, and a hollow tapering portion connecting and gradually merging with said hub and cannula, those steps which comprise die-pressing a disc-like piece of sheet metal into the form of an elongated cup which corresponds to the'required dimensions of the hub-like portion, in further diepressing the bottom of said cup to taper the same to the desired dimensions of said connecting portion, and in then reducing and elongating the bottom of said tapered portionwhilepreserving said desired form and dimensions of said cup and connection portions to provide a line axial cannula tube integral with said connecting portion.

2. The method of claim -1 in which the bottom oi the tapered portion is reduced and elongated swaging the end of said tapering portion to a line integral cannula tube, said tapering portion connecting and gradually merging with said hub and cannula portions both exteriorly and interioriy whereby the inner surfaces of the needle hub, cannula and tapering connecting portions are lormed continuously smooth, for the free flow of fluid therethrough and the bending stresses of cannula penetration are provided distribution through a substantial zonal length of the integral wall of such a needle.

. JESSE CONRAD SMITH. 

